Fix GitHub Actions typo: pull_quest → pull_request

[swharden]

This PR replaces pull_quest with pull_request, affecting 3 pages:

• https://docs.microsoft.com/en-us/dotnet/devops/dotnet-build-github-action
• https://docs.microsoft.com/en-us/dotnet/devops/dotnet-secure-github-action
• https://docs.microsoft.com/en-us/dotnet/devops/dotnet-test-github-action

To be sure I double-checked and confirmed there is no such thing as a pull_quest
https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows

[gewarren]

Thank you @swharden